In a typical electrophotographic printing process, a photoconductive member is charged to a substantially uniform potential so as to sensitize the surface thereof. The charged portion of the photoconductive member is exposed to a light image of an original document being reproduced. Exposure of the charged photoconductive member selectively dissipates the charges thereon in the irradiated areas. An electrostatic latent image is formed on the photoconductive member corresponding to the informational areas contained within the original document. After the electrostatic latent image is recorded on the photoconductive member, the latent image is developed by bringing a developer material into contact therewith. Generally, the developer material comprises toner particles adhering triboelectrically to carrier granules. The toner particles are attracted from the carrier granules to the latent image forming a toner powder image on the photoconductive member. The toner powder image is then transferred from the photoconductive member to a copy sheet. The toner particles are heated to permanently affix the powder image to the copy sheet.
In printing machines such as those described above, a bias charge member roller (BCR) is increasingly used as the major charging apparatus in xerographic systems due to environment friendliness and excellent charging performance. A BCR provides several advantages over traditional scorotron charging: a) uniform and stable charging; b) reduced emissions of ozone or other corona by-products; c) lower AC/DC voltage supply requirements; and d) reduced service maintenance.
The BCR suffers, however, from toner/additive contamination over many printing cycles reducing overall service life of BCR. Significant amounts of effort have been put to suppress the contamination on BCR. For example, U.S. Pat. Nos. 8,126,344; 7,711,285; 7,526,243; 7,266,338; 7,079,786; 6,836,638; 6,470,161 are using dedicated cleaning systems to alleviate the adherence of particles trapped on the cleaning surface of a photoreceptor. On the other hand, U.S. Pat. No. 8,116,655, US20090169237, U.S. Pat. No. 6,381,432, US20040019986, U.S. Pat. Nos. 7,899,354, 8,064,791, US20110170896, US20110170897 propose direct cleaning systems to clean BCR surface for extended lifetime.